Light sensitive derivatives of vat dyestuffs and a process of preparing them



Patented June 1, 1937 PAT ENT; 'O-FFICE LIGHT SENSITIVE DERIVATIVES F VAT DYESTUFFS AND A PROCESS OF PREPAR- ING THEM Paul Ochwat,

Frankfort-on-the-Main-Hochst,

and Bruno Wendt, Dessau, Germany, assignors to Agfa Ansco Corporation, Binghamton, N. Y., a corporation of New York 1 No Drawing. Application January 6, 1933, Serial No. 650,590. In Germany January 11, 1932 10 Claims.

The present invention relates to light-sensitive derivatives of vat-dyestuffs and a process of preparing them. I

We have found that light-sensitive substances of valuable properties are obtainable by reacting a water-soluble salt of a leuco ester of a vat dyestuff, the ester being formed by means of a polybasic inorganic acid, upon a water-soluble salt of an N-nitrosoearyl-hydroxylamine, aryl being of the benzene series, in the presence 01' an inert solvent. When using an ester salt of a leuco vat dyestuff with a. volatile base, the base may be removed, if desired, by distillation from the reaction mixture.. The constitution of the new light-sensitive substances is not known. They are applicable with advantage for photographic purposes, for instance, for the production' of multi-color pictures.

Light-sensitive layers maybe prepared, for instance, in one of the following Ways: The new products'above mentioned may be incorporated with a suitable binding agent such as, gelatine, glue, collodion or the like, and this mixture may be applied on a support; or the said new prod- 25 ucts may be produced by combining the estersalts of the leuco vat dyestuffs and the salts of N-nitroso-aryl-hydroxylamines in a layer of a binding. agent which has already been applied on a support; or the products are incorporated with or produced, without formation of a layer, in paper, cellulosehydrate-sheets or the like.

The reaction between an ester salt of a leuco vat dyestuff with a base, such as pyridine, on the one hand, and with a salt of N-nitroso-arylhydroxylamine, on the other hand, may be performed, for instance, by removing with steam the volatile base from the aqueous solution or suspension of the components; By evaporation, the new products are obtainable in the form of powders easily soluble in water.

It has already been proposed to produce lightsensitive layers by means of alkali salts of sulfuric acid esters of leuco vat dyestuffs. The layers obtainable according to the present invention have over the said known layers the advantage of yielding a better gradation and purer lights and of being more stable in the dark.

According to our new process cellulose hydrate films or sheets may be used with special advantage for the production of one-color or multicolor pictures. As illustrated in the following examples, the sheets are impregnated at ordinary or raised temperature with the respective solution. By applying an elevated temperature, the impregnation is accelerated, which is also the case by adding a precipitant, such as sodium sulfate, in a quantity insufficientfor precipitation. The addition of glycerine to the impregnating liquor renders the d fy ,Sheet's pliable and increases, by its humidifying action, the sensitiveness of the light-sensitive cornpound; This latter advantage may'also be achieved by the addition of another hygroscopic substance. In the photography of natural colors there are used separate sheets containing incorporated therewith according to one of the above mentioned methods the, derivatives'of the leuco compounds ofa yellow, a purple-red and a bluish-green respectively, dyestufi, which sheets after being printed, fixed and, advantageously, impregnated with a glycerine solution are glued together one on the other in known" manner, for instance, by means of gelatine solution on paper.

Cellulose-derivative'films or sheets which superficially have been rendered sensitive to water by means of a saponifying agent, for instance, an acetyl or a nitro-acetate film, may be used in an analogous manner. When used for the multi-color photography or for the production of' anaglyphic pictures the 'two or more partial pictures, the two stereo pictures respectively, are printed in succession one above the other on a material sensitized in accordance with the invention in such a'manner that after the first printing operation the print is fixed by washing with water and the material is-sensitized for the next printing operation and so on.

The following examples serve toillustrate the invention, but they are not intended to limit it thereto, the parts being by weight:

(1) Into a. solution containing mol. of the sodium salt of the sulfuric acid ester of leuco- 4.4'-dichloro-5.5'-dibromindigo there is introduced pyridine hydrochloride, until the dyestuif has been precipitated as difiicultly soluble pyridine salt. The latter is isolated, made into" a paste with water, mol. of the 'sodium salt of N-nitroso-phenyl-hydroxylamine as well as a excess thereof are added, and steam is passed through the whole until pyridine no longer distils over.

There is obtained a solution from which the new product may be obtained by evaporation. It forms a powder which is easily solublein water, when the solution is heated with dilute acids, the vat dyestuff precipitates. In materials impregnated with said solution the vat dyestufi is re-formed on exposure to light.

In the same manner the sulfuric acid esters of other leuco vat dyestuffs may be used for the preparation of new products. Instead of N- nitroso-phenyl-hydroxylamine there may also be used the derivatives and substitution products thereof.

(2) In similar manner a light sensitive product may be prepared from: 4 grams of the sodium salt of the sulfuric acid ester of leuco 4.4.:

ammonium salt of N-nitroso-phenyl=hydroxylamine, 20 cc. of glycerine and cc. of water.

(3) 4 grams of the sodium salt of phosphoric acid ester of leuco 4.4'dimethyl-6.6'-dichlorthioindigo are dissolved in amixture of 40cc. of glycerine and 60 cc. of water and there is added to the solution 1 gram of the sodium salt of N'- nitroso-para-chlorphenyl-hydroxylamine. With this solution cellulose hydrate sheets are impregnated for 10 minutes at room temperature and then dried. After printing, whereby a purplered picture with pure lights is obtained, the sheets are washed with warm water, whereby the unexposed substance is removed.

(4) A cellulose hydrate sheet is impregnated with a solution prepared from 5 kilos of the sodium salt of the sulfuric acid ester of leuco 4.4- dimethyl-5.7.6'-trichlorthioindigo, 2 kilos of the sodium salt of N-nitroso-phenyl-hydroxylamine, 40 liters of glycerine and liters of water. After squeezing oif the adherent solution, the sheet is dried, rolled up and cut to the desired sizes. By printing a negative on one of the sheets, a bluish-red picture of very good gradation and pure lights is obtained, it is washed for 5 minutes in water of 70 C. and thereby fixed.

We claim:

1. The process which comprises mixing the sodium salt of the sulfuric acid ester of leuco 4.4-dimethy1-5.7.6'-trichlorothioindigo with the sodium salt of N-nitroso-phenyl-hydroxylamine in the presence of water and glycerol.

2. The process which comprises mixing the sodium salt of phosphoric acid ester of leuco 4.4- dimethyl-6.6'-dichlorothioindigo with the sodium salt of N-nitroso-para-chlorophenyl-hydroxylamine in the presence of water and glycerol.

3. The process which comprises mixing the sodium salt of the sulfuric acid ester of leuco 4.4- dichloro-5.5-dibromo-indigo with the ammonium -salt of N-nitroso-phenyl-hydroxylamine in the presence of water and glycerol.

4. The compounds identical with those which are obtainable by mixing the sodium salt of the sulfuric acid ester of leuco 4.4-dimethy1-5.7.6' trichlorothioindigo with the sodium salt of N- nitroso-phenyl-hydroxylamine in the presence of water and glycerol said compounds being valuable'light-sensitive substances for photographic purposes.

5. The compounds identical with those which are obtainable by mixing the sodium salt of phosphoric acid ester of leuco 4.4'-dimethyl-6.6'-

dichlorothioindigo with the sodium salt of N- nitroso-para-chlorophenyl-hydroxylamine in the presence of water and glycerol said compounds being valuable light-sensitive substances for photographic purposes.

6. The compounds identical with those which are obtainable by mixing the sodium salt of the dichloro-5.5-dibromindigo, 4 grams of the sulfuric acid ester of leuco 4.4'-dichloro-5.5'- dibromoindigo with the ammonium salt of N- nitroso-phenyl-hydroxylamine in the presence of water and glycerol said compounds being valuablelight-sensitive substances for photographic purposes.

7. The process which comprises reacting a water-soluble salt of a leuco ester of a vat dyestufi of the group consisting of 4.4'-dimethyl-5.7.6'- trichlorothioindigo, 4.4'-dimethyl-6.6'-dichlorothioindigo and 4.4-dichloro-5.5'-dibromoindigo, the ester being formed by means of an acid of the group consisting of sulfuric and phosphoric acid, upon a water-soluble salt of an N-nitroso-arylhydroxylamine, said aryl comprising a benzene ring, in the presence of an inert solvent.

8. The process which comprises reacting a water-soluble salt of a leuco ester of a vat dyestufi of the group consisting of 4.4'-dimethyl-5.7.6'- trichlorothioindigo, 4.4-dimethyl-6.6'-dichloroa thioindigo and 4.4-dichloro-5.5-dibromoindigo, the ester being formed by means of an acid of the group consisting of sulfuric and phosphoric acid, upon a water-soluble salt of an N-nitrosophenyl-hydroxylamine in the presence of an inert solvent.

' 9. The compounds identical with those which are obtainable by reacting a water-soluble salt of a leuco ester of a vat dyestuff of the group consisting of 4.4-dimethyl-5.7.6'-trichlorothioindigo, 4.4-dimethyl-6.6'-dichlorothioindigo and 4.4-dichloro-5.5'-dibromoindigo, the ester being formed by means of an acid of the group consisting of sulfuric and phosphoric acid, upon a water-soluble salt of an N-nitroso-aryl-hydroxylamine,.said aryl comprising a benzene ring, in the presence of an inert solvent, said compounds being valuable light-sensitive substances for photographic purposes.

10. The compounds identical with those which are obtainable by reacting a water-soluble salt of a leuco ester of a vat-dyestuff of the group consisting of 4.4-dimethyl-5.7.6-trichlorothioindigo, 4.4 dimethyl 6.6'-dichlorothioindigo, 4.4-dichloro-5.5'-dibromoindigo, the ester being formed by means of an acid of the group consisting of sulfuric and phosphoric acid, upon a water-soluble salt of an N-nitroso-phenyl-hydroxylamine in the presence of an inert solvent, said compounds being valuable light-sensitive substances for photographic purposes.

PAUL OCHWAT. BRUNO WENDT. 

